The Quiet Courtship Of Mountain Pine Beetles

The file a beetle rubs against its the scraper on its hard wing covering in order to chirp, or stridulate.

Credit Malcolm M. Furniss and Parks Canada

Pine beetle chirps are too quiet for humans to hear, but they play an important role in beetle courtship.

"Upon finding a suitable tree, the female pine beetle will begin constructing a gallery of tunnels inside the bark. She then emits pheromones to attract a male for mating. A male pine beetle arrives quickly and finds the female inside her gallery. The male then gives a courtship chirp to win her over. To make the sound, the male rubs a rasp-like file on the top of his abdomen against the inside of the hard wing covering. The male guards the gallery from other would-be suitors. If another male enters, a violent wrestling match ensues, and both males emit wild, aggressive chirps.

It's important to remember that pine beetle chirps are so quiet that, without tools like a highly sensitive microphone placed inside the tree's bark, we are unable to hear them."